Mark Todd, co-founder of switching website energyhelpline.com, said firms were wrong to simply say that the housing stock was the problem and they must take responsibility for putting up prices of gas and electricity.
His comments came after npower's Paul Massara said the actual unit prices of gas and electricity in the UK are among the lowest in Europe - but bills are high "because British houses waste so much energy".
Mr Todd said: "The reason why UK energy bills are high is both that the housing stock is not energy efficient but also that suppliers have kept whacking up prices year after year.
"Suppliers have raised prices by 140% in the last nine years while users have cut usage. Typical gas usage is down 34% and electricity consumption by 3% and this is in part because many customers can no longer afford to heat their homes.
"It's crunch time for the energy market and suppliers can't just blame the houses."
Npower announced a 10% average bill increase in the latest round of price rises late last year, affecting about 3.1 million customers, but has said that it will reduce bills as a result of a shake-up of Government green levies.
Asked whether David Cameron agreed that draughty homes were to blame for some of the cost of bills, the Prime Minister's official spokesman said: "What the Prime Minister would say is that he would keep talking about what the Government is doing - £50 off the average bill, legislation to put people onto the cheapest tariffs, the annual competition review.
"What the PM wants is downwards pressure on everyone's bills."